Process for the reproduction of sounds recorded by means of photograms



D86. 17, 1935. v R BERTHQN 2,024,563

PROCESS FOR THE REPRODUCTION (37 SOUNDS RECORDED BY MEANS OF PHOTOG-RAM-S Filed July 8, 1930 Patented Dec. 17, 1935 PATENT OFFICE PROCESS FOR THE REPRODUCTION SOUNDS RECORDED BY MEANS OF PHO- TOGRAMS Rodolphe Eerthon, Neuilly sur Seine, France, assignor, by mesne assignments, to Kislyn Corporation, New York, N. Y., a corporation of Delaware Application July 8, 1930, Serial No. 466,535 In France July 18, 1929 1 Claim.

The examination of a photographic negative shows that two main alterations have intervened in the course of the developing and the succeeding processes, viz.: the points where the silver bromide has been reduced to metallic silver noW display better conductive properties of electricity while at the same time they have undergone a kind of contraction due to a real tanning process. The development of the argentic image thus results in a twofold variation, namely, a variation in the electric conductivity and a variation in the relief.

The electric conductivity may be increased by using a developer which will produce a more plentiful metal deposit on the photograms (physical developer). The reliefs may be increased by using such a developer as hydroquinone and caustic potash, hydroquinone and saccharate of lime, etc.

Figure 1 illustrates a view of the record showing the electrodes.

Figure 2 illustrates a cross-sectional view through the sound record on line XY.

If a sound photogram be recorded lengthwise of a film by the constant-surface variable-density process, two facts will be observed. First of all, by arranging a pair of rheophores a and b in close proximity to each other so that they bear upon either side of the sound record in the manner shown in Fig. 1, it will be observed that whenever a dark line of reduced silver happens to connect the points of contact of the rheophores, and provided the electric supply to which same are connected is of sufiicient tension, a current will fiow through the rheophores which is the more intense as the line between the points of contact is darker. In addition, considering the cross sectional view of the film taken on line XY in Fig. l as shown in Fig. 2, it will be seen that the same is similar in shape to the bottom of the groove in certain gramophone records: A designates the celluloid layer or base which, as is well known in the art, is of non-electrical conducting qualities, B designates the gelatine or emulsion coating the exposed surface of which is corrugated as a result of the action of the developer.

This invention relates to the utilization of such 1 superficial alterations of the emulsion to trans- 5 fer them into electric-dynamic variations adapted tocontrol a loud speaker.

The simplest method consists in using a pair of rheophores arranged in very close relation to each other and made e. g. of iridio-platinum, or a pair of semi-conductive crystals (carborum dum, etc.) connected to an electric supply of sufficient tension (80 to 150 volts) the circuit having connected therein a relay or an amplifier adapted to control a loud speaker directly or indirectly.

If the variations in the relief are utilized instead of the variations in the conductiveness, a pick-up device followed with an amplifier will be substituted for the rheophores.

In no one of such cases does the selected arrangement take advantage of the photogram transparency, which does away with all the drawbacks incident to the use of selenium or potassium cells and the so painstaking adjustments necessary.

It is to be understood that'the invention is applicable not only to ordinary films but also to films provided with microscopic refringement elements for colour photography according to R. Berthons process.

I claim:

In combination, a film having a base of nonelectrical-conducting material and an emulsion of material which is conducting when developed, a sound track extending longitudinally of said emulsion and having variations in electrical conductivity corresponding to fluctuations in the sound recorded thereon, and. an electric amplifying circuit interrupted at the track and having a pair of contacts opposite each other and engaging the developed emulsion of the track and adjacent opposite side edges thereof.

RODOLPHE BERTHON. 

